@article{ToalaBowmanVanReethetal.2022,
  author    = {Toal{\´a}, Jes{\´u}s Alberto and Bowman, Dominic and Van Reeth, Timothy and Todt, Helge Tobias and Dsilva, Karan and Shenar, Tomer and Koenigsberger, Gloria Suzanne and Estrada-Dorado, Sandino and Oskinova, Lida and Hamann, Wolf-Rainer},
  title     = {Multiple variability time-scales of the early nitrogen-rich Wolf-Rayet star WR 7},
  series = {Monthly notices of the Royal Astronomical Society},
  volume    = {514},
  journal   = {Monthly notices of the Royal Astronomical Society},
  number    = {2},
  publisher = {Oxford University Press},
  address   = {Oxford},
  issn      = {0035-8711},
  doi       = {10.1093/mnras/stac1455},
  pages     = {2269 -- 2277},
  year      = {2022},
  abstract  = {We present the analysis of the optical variability of the early, nitrogen-rich Wolf-Rayet (WR) star WR 7. The analysis of multisector Transiting Exoplanet Survey Satellite (TESS) light curves and high-resolution spectroscopic observations confirm multiperiodic variability that is modulated on time-scales of years. We detect a dominant period of 2.6433 +/- 0.0005 d in the TESS sectors 33 and 34 light curves in addition to the previously reported high-frequency features from sector 7. We discuss the plausible mechanisms that may be responsible for such variability in WR 7, including pulsations, binarity, co-rotating interaction regions (CIRs), and clumpy winds. Given the lack of strong evidence for the presence of a stellar or compact companion, we suggest that WR 7 may pulsate in quasi-coherent modes in addition to wind variability likely caused by CIRs on top of stochastic low-frequency variability. WR 7 is certainly a worthy target for future monitoring in both spectroscopy and photometry to sample both the short (less than or similar to 1 d) and long (greater than or similar to 1000 d) variability time-scales.},
  language  = {en}
}
@article{RubioToalaTodtetal.2022,
  author    = {Rubio, Gabriel and Toal{\´a}, Jes{\´u}s Alberto and Todt, Helge Tobias and Sabin, Laurence and Santamar{\´i}a, Edgar and Ramos-Larios, Gerardo and Mart{\´i}n Guerrero, Jos{\´e} David},
  title     = {Planetary nebulae with Wolf-Rayet-type central stars - IV. NGC 1501 and its mixing layer},
  series = {Monthly notices of the Royal Astronomical Society},
  volume    = {517},
  journal   = {Monthly notices of the Royal Astronomical Society},
  number    = {4},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0035-8711},
  doi       = {10.1093/mnras/stac3011},
  pages     = {5166 -- 5179},
  year      = {2022},
  abstract  = {Theory predicts that the temperature of the X-ray-emitting gas (similar to 10(6) K) detected from planetary nebulae (PNe) is a consequence of mixing or thermal conduction when in contact with the ionized outer rim (similar to 10(4) K). Gas at intermediate temperatures (similar to 10(5) K) can be used to study the physics of the production of X-ray-emitting gas, via C iv, N v, and O vi ions. Here, we model the stellar atmosphere of the CSPN of NGC 1501 to demonstrate that even this hot H-deficient [WO4]-type star cannot produce these emission lines by photoionization. We use the detection of the C iv lines to assess the physical properties of the mixing region in this PNe in comparison with its X-ray-emitting gas, rendering NGC 1501 only the second PNe with such characterization. We extend our predictions to the hottest [WO1] and cooler [WC5] spectral types and demonstrate that most energetic photons are absorbed in the dense winds of [WR] CSPN and highly ionized species can be used to study the physics behind the production of hot bubbles in PNe. We found that the UV observations of NGC 2452, NGC 6751, and NGC 6905 are consistent with the presence mixing layers and hot bubbles, providing excellent candidates for future X-ray observations.},
  language  = {en}
}
@article{ToalaRamosLariosGuerreroetal.2019,
  author    = {Toal{\´a}, Jes{\´u}s Alberto and Ramos-Larios, Gerardo and Guerrero, Martin A. and Todt, Helge Tobias},
  title     = {Hidden IR structures in NGC40},
  series = {Monthly notices of the Royal Astronomical Society},
  volume    = {485},
  journal   = {Monthly notices of the Royal Astronomical Society},
  number    = {3},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0035-8711},
  doi       = {10.1093/mnras/stz624},
  pages     = {3360 -- 3369},
  year      = {2019},
  abstract  = {We present the analysis of infrared (IR) observations of the planetary nebula NGC40 together with spectral analysis of its [WC]-type central starHD826. Spitzer IRS observations were used to produce spectral maps centred at polycyclic aromatic hydrocarbons (PAH) bands and ionic transitions to compare their spatial distribution. The ionic lines show a clumpy distribution of material around the main cavity of NGC40, with the emission from [Ar II] being the most extended, whilst the PAHs show a rather smooth spatial distribution. Analysis of ratio maps shows the presence of a toroidal structure mainly seen in PAH emission, but also detected in a Herschel PACS 70 mu m image. We argue that the toroidal structure absorbs the UV flux from HD826, preventing the nebula to exhibit lines of high-excitation levels as suggested by previous authors. We discuss the origin of this structure and the results from the spectral analysis of HD826 under the scenario of a late thermal pulse.},
  language  = {en}
}
@article{IgnaceToalaOskinova2015,
  author    = {Ignace, R. and Toal{\´a}, Jes{\´u}s Alberto and Oskinova, Lida},
  title     = {Inversion of Intensity Profiles for Bubble Emissivity},
  series = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015},
  journal   = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-88432},
  pages     = {358},
  year      = {2015},
  abstract  = {Under the assumption of spherical symmetry, the run of intensity with impact parameter for a spatially resolved and optically thin bubble can be inverted for an "effective emissivity" as a function of radius. The effective emissivity takes into account instrumental sensitivity and even interstellar absorption. This work was supported by a grant from NASA (G03-14008X).},
  language  = {en}
}
@article{ToalaGuerreroChuetal.2015,
  author    = {Toal{\´a}, Jes{\´u}s Alberto and Guerrero, Mart{\´i}n A. and Chu, Y.-H. and Arthur, S. J. and Gruendl, R. A.},
  title     = {Diffuse X-ray Emission within Wolf-Rayet Nebulae},
  series = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015},
  journal   = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-88316},
  pages     = {333 -- 336},
  year      = {2015},
  abstract  = {We discuss our most recent findings on the diffuse X-ray emission within Wolf-Rayet (WR) nebulae. The best-quality X-ray observations of these objects are those performed by XMM- Newton and Chandra towards S 308, NGC 2359, and NGC 6888. Even though these three WR nebulae might have different formation scenarios, they all share similar characteristics: i) the main plasma temperatures of the X-ray-emitting gas is found to be T =[1-2]×^K, ii) the diffuse X-ray emission is confined inside the [O iii] shell, and iii) their X-ray luminosities and electron densities in the 0.3-2.0 keV energy range are LX ≈10^33-10^34 erg s-1 and ne ≈0.1-1 cm^-3 . These properties and the nebular-like abundances of the hot gas suggest mixing and/or thermal conduction is taking an important r{\^o}le reducing the temperature of the hot bubble.},
  language  = {en}
}